1. Field of the Invention
This invention relates to freight containers. Specifically, and not by way of limitation, the present invention relates to a device, method and system for detecting shell cracks on freight containers.
2. Description of the Related Art
In recent years, due to an increasing number of international smuggling occurrences and terrorist attacks, security of freight containers has received more attention. Generally, a freight container is composed of a front end, side walls, a roof, a base structure and a door end. Terrorist may make holes in any of these six surfaces of the containers, which may cause significant problems for container services. In addition, there is a concern on how to prevent criminals from exploiting containers to commit crimes, avoid the necessity of re-encasing goods in the containers that have been examined sealed by customs, and enable a prompt alarm after a container is damaged illegally. Thus, one of the key directions for the containers industry is to design and develop containers that are secure and have an intelligent detection function.